I have both a Corsair II w/ external VFO (last production run) and an OMNI
VI+.
They are very close as receivers although how they achieve the sensitivity,
selectivity, in large signal environments is vastly different. Overall the
Corsair II seems quieter with a lower noise floor. Both receivers have 2.4
kHz, 1.8 kHz, 500 Hz, and 250 Hz filters for Passband tuning. The Omni VI+
has a 9 MHz first IF with 2.4 kHz
(standard), 500 Hz, and 250 Hz filters.
The Corsair II with a PTO and cascaded crystal filters is limited in large
signal rejection only by the filter skirt shape and AGC action while
listening to a very weak CW signal. The offset to some of the station
ergonomics is the ability to dual receive using both VFOs (both use the same
filter, IF, AGC settings).
The OMNI VI+ with master crystal & PLL frequency synthesis, is susceptible to
a raised noise floor from IMD created by large signals in the 1st IF (common
to all synthesized receivers) unless the roofing filter rejects close in
large signals. TenTec for that reason provides narrow roofing filters in the
first IF. With the 500 Hz or more likely the 250 Hz filters selected, a S0-S1
CW signal is copied easily with big signals in a pileup starting 1 kHz up.
For contesting and DXing with frequent band changes the OMNI VI+ is my first
choice. For S-3 to S-9 signal DXing with large pileups almost requiring dual
receive to "be where they are listening" the dual VFO Corsair II is the only
choice.
Its an individual choice, but for the buck, Corsair IIs are hard to beat.
Gary Huber - AB9M@aol.com
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